1. Field of the Invention
The present invention relates to method and apparatus for recording and/or reproducing a PCM (pulse-code-modulated) signal.
2. Description of the Prior Art
In a video tape recorder (hereinafter simply referred to as VTR) of 1 (or 1.5) rotary head type using a magnetic tape of 1-inch wide, that is, a VTR using so-called SMPTE type C format, two heads are mounted on a rotary drum, this rotary drum is rotated at a revolution rate of one rotation per one field and a magnetic tape is obliquely wrapped around the peripheral surface of this rotary drum with an angle of substantially 360 degrees and transported at a predetermined speed. Of the above mentioned two heads, the video signal is recorded by one head during its video period, while a vertical synchronizing signal is recorded by another auxiliary head during the synchronizing period in which the former head is detached from the magnetic tape.
By the way, in such format, if a so-called time-base corrector is used for a reproduced signal, even when the signal in the synchronizing period is dropped, the normal video signal can be reproduced without trouble if the signal in the video period is obtained. Therefore, it is proposed that in the above mentioned format, instead of the signal in the synchronizing period, a PCM (pulse-code-modulated) digital audio signal be recorded on a skewed track which is narrow in width.
That is, according to the prior art format as described above, the audio signal is recorded in the form of an analog signal by a fixed or stationary head. In such analog recording, especially if the dubbing operation for dubbing an analog audio signal recorded is carried out repeatedly, the quality of the analog audio signal is deteriorated considerably. While, if the audio signal is recorded in the form of a digital signal, it is possible to remove the foregoing problem that the quality of the audio signal is deteriorated in the dubbing operation.
The above mentioned system is disclosed, for example, in Japanese Laid Open Patent Application No. 57-119571.
However, in order to record an audio data of one field period on the synchronizing signal track, the digital data must be timebase-compressed very much and then recorded. This makes the signal processing very difficult. In addition, the recording density becomes large so that the above mentioned system is difficult to realize in the recording and/or reproducing system.